The present invention relates to processing of a signal transmitted in a bitstream and an apparatus for processing the signal.
Analog signals in a real-world system are sampled, quantized, and converted into digital signals to transmit the digitized version of the analog signals. Transmitting the digital signals improves the quality of the sound or image but increases the amount of data.
The digital signals can be compressed to compensate for the increase in the amount of data during digitization. Without such data compression, channel bandwidths needed to transmit the digital image information or audio information are not available, making it impossible or difficult to transmit the digital image information or audio information. In this regard, various types of compression methods can be used including representative compression methods such as JPEG regarding still images or MPEG regarding motion pictures.
Because a transmission bit rate or a real-time processing bit rate is determined according to the characteristics of a transmission channel, the compressed data is transmitted in a state where maximum sound quality or maximum image quality is secured at the determined bit rate. Therefore, decoders for optimally restoring the transmitted data and encoders for encoding the data to effectively use a transmission rate can be used.
Also, the compressed digital signal is transmitted in a bitstream that has a continuously transmitted bit rate, and the transmitted bitstream is restored to original signals by a decoder included in a receiving terminal during which a bitstream error often occurs. For example, when the bitstream is transmitted to a wireless network in which errors easily occur among a variety of heterogeneous networks, the bitstream error may occur due to a transmission error at a receiving side.
Due to the bitstream error, the bitstream may not be partially or completely restored when the hardware decoder decodes or decrypts the bitstream. For example, the bitstream error causes a partially broken image or sound that is harsh to the ears. Furthermore, the hardware decoder may be unavailable or a wrong calculation may destabilize a system.